There have conventionally been developed various backlight units that provide light to a liquid crystal display panel (a non-self-luminous display panel) of a liquid crystal display device. An example of the backlight units is, as shown in FIG. 9, a backlight unit 149 of the side light type (a backlight unit 149 of a type which light enters a side surface 142S of a light guide plate 142) disclosed in Patent Document 1.
In the backlight unit 149, light to be provided to a liquid crystal display panel 159 is obtained from an LED (light emitting diode) 112. The LED (light-emitting element) 112 is compact, and is commonly used in backlight units 149 available these days. Particularly, in mobile tools such as portable terminals, the LED 112 in particular is used commonly.
As shown in a perspective view of FIG. 10, the LED 112 is often mounted on a mounting board 111 having flexibility (such a mounting board 111 on which the LED 112 is mounted is also referred to as an LED module mj). If the mounting board 111 having flexibility is excessively long, the mounting board 111 flexes more than necessary.
For example, when the LED module mj is mounted in a backlight unit 149 for a notebook personal computer (notebook PC) which is larger than a cellular phone, the mounting board 111 may flex. Specifically, during manufacture of the notebook PC, a mounting board 111 with an excessive length may flex. Moreover, when the mounting board 111 flexes, the LED 112 may come off from the mounting board 111, and a defective product may be produced.
One approach to avoid such a situation is, as shown in a perspective view of FIG. 11A, connecting a relatively short mounting board 111 by use of a flexible flat cable (FFC) 114. In this way, the mounting board 111 is less likely to flex excessively.    Patent Document 1: JP-A-2006-11242